The lithium manganese dioxide cell, as disclosed in U.K. GB 2,222,480, can be made in the form of a commercial cell. The cell has a long shelf life, is compact and provides about 3 Volts.
The lithium electro-chemical cell of the present invention has an anode and a cathode arranged alternately in layers, a separator disposed between adjacent said layers and an organic electrolyte, the anode, cathode and separator having a structure in which the anode, cathode and separator comprise respective strips wound to form a solid spiral winding, and the outermost electrode layer being thinner than the respectively, more inwardly disposed corresponding electrode layers. The separator comprises two layers, a shutdown separator and a glass fiber mat insulator. The organic electrolyte is an organic solvent mixture in which a conducting salt has been dissolved.
At least, the lithium dioxide D cell of the present invention can meet requirements of the UN Recommendations on the Transport of Dangerous Goods: Manual of Test and Criteria (UN Document ST/SG/AC.10/11).
The present invention is an improvement of the Cell of UK Patent No. GB2,222,480. In order to make the lithium manganese dioxide cell safe in a better form for commercial and military use and non-hazardous for transportation, there must be short circuit protection.
Integrated into the cell construction of the present invention is a resettable positive temperature coefficient fuse. The positive temperature coefficient fuse, which can withstand shock and mechanical vibration without damage, is mounted in such a way that it cannot be bypassed without destroying the cell. If the cell is shorted out, within a few seconds, the positive temperature coefficient fuse limits the fault current to a low value, which will never allow the cell to overheat or vent.
If the cell is charged and starts to overheat, the positive temperature coefficient fuse will again switch to a high resistance state and limit the charging current to a value which will prevent overheating and venting.
When the short or the charging voltage is removed, within a few minutes, the positive temperature coefficient fuse recovers and the cell is again fully functional and capable of meeting all the tests given in the UN Manual of Tests and Criteria, Part III, sub-section 38.3.